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SUMMARY:Cooling Nano-electronic Devices to Ultra-Low Temperatures - Dr Lev
  Levitin\, Royal Holloway University of London
DTSTART:20170515T131500Z
DTEND:20170515T141500Z
UID:TALK70783@talks.cam.ac.uk
CONTACT:Teri Bartlett
DESCRIPTION:Predicted order in low-dimensional electron systems\, such as 
 antiferromagnetic and crystalline quantum wires\, non-Abelian fractional Q
 uantum Hall States\, and Bose-Einstein condensation of excitons in electro
 n-hole bilayers\, as well as expected improved performance of devices sens
 itive to thermal noise\, motivates the development of techniques for cooli
 ng electrons in nanostructures into low millikelvin and micro-kelvin regim
 e.\n\nIn a conventional dilution refrigerator with a base temperature of 5
 -20 mK the electrons in a nanostructure typically reach tens of mK. With t
 he goal of reducing this figure below 1 mK we cool a sample in a helium-3 
 immersion cell mounted on a nuclear demagnetisation cryostat with a 0.3mK 
 base temperature. In the prototype experiment a simple 2DEG sample is cool
 ed via large Ohmic contacts and its temperature is measured with a noise t
 hermometer attached via another contact. We investigate thermal transport 
 in 2DEG and Ohmic contacts and derive a thermal model relating the tempera
 tures of the sample and thermometer. This gives the electron temperature e
 stimate of 1.5 mK achieved after reducing the heat leak to the sample to f
 ew femtowatt.\n\nI will review the principles of dilution and demagnetisat
 ion refrigerators\, and noise thermometry\, compare our approach to coolin
 g nanostructures to those taken by other groups\, and discuss the proposed
  experiments in quantum point contacts.\n\n\nFigure 1: Inside the He3 imme
 rsion cell\n
LOCATION:Mott Seminar Room (Mott Building Room 531)\, Cavendish Laboratory
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